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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have investigated the role of serotonergic neurons on the astrocytes catabolism of glutamate by analyzing glutamine synthetase (GS) and glutamate dehydrogenase (GDH) expression in the hippocampus after the degeneration of serotonergic neurons by a specific neurotoxin (5,7-DHT). 5,7-DHT caused reactive gliosis with hypertrophy (increase in glial fibrillary acidic protein (GFAP) expression) but not proliferation of astrocytes. Glutamate metabolism appeared preferentially regulated by a control of GDH expression rather than GS since the expression of GDH was specifically and significantly induced in the hippocampus whereas the level of GS remained unchanged. The inhibition of serotonin synthesis (by para-chlorophenylalanine (p-CPA) administration) produced no significant increase of GDH level. This suggests that serotonin is not the principal factor involved in this control of GDH expression.
Brain Res Mol Brain Res 1994 Oct
PMID:Modifications of glial metabolism of glutamate after serotonergic neuron degeneration in the hippocampus of the rat. 785 35

The time course variations in tyrosine hydroxylase (TH) activity and specific mRNA were measured in the rat locus coeruleus (LC) and substantia nigra after an intracerebroventricular (i.c.v.) injection of 5,6-dihydroxytryptamine (5,6-DHT), a neurotoxin known to selectively destroy serotoninergic neurons. In this study, the TH activity and TH mRNA were both analyzed from homogenates of single tissue samples (micropunches). TH mRNA was extracted and quantified by densitometry using a northern blot method and an artificial TH RNA as an external standard. 5,6-DHT injection led to a long-lasting increase in TH activity and TH mRNA in LC but not in substantia nigra. The elevation in LC was progressive and reached its maximum value (+75%) at day 4 and day 8 after 5,6-DHT. This effect on TH activity was accompanied by a parallel change in TH mRNA whose amplitude was +57%, +81% and +45% at day 2, 4, and 8 respectively after the neurotoxin injection. Return to normal values was observed at day 16. Variations in TH activity and TH mRNA in LC were of similar amplitude. These results suggest that serotonin could be a potent modulator of TH gene expression within noradrenergic LC neurons.
Brain Res Mol Brain Res 1994 Mar
PMID:Long-term alteration in tyrosine hydroxylase mRNA levels in rat locus coeruleus after intraventricular injection of 5,6-dihydroxytryptamine. 791 98

The structures of cDNA clones encoding four members of the rat 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD) family were characterized. The rat type I, type II and the novel type IV are genuine NAD+/H-dependent 3 beta-HSD isoenzymes. On the other hand, the liver-specific type III protein is a specific 3-keto-reductase (3-KSR) that catalyzes the conversion of 5 alpha-androstane-3-one-17 beta-ol (DHT) and 5 alpha-androstane 3,17-dione (A-dione) into their 3 beta-hydroxy metabolites. The aim of the present study was to further characterize the enzymatic properties of rat types I, III and IV, especially their role in the formation and degradation of DHT after transient expression in intact human HeLa cervical carcinoma, JEG-3 choriocarcinoma or SW-13 adrenal cortex adenocarcinoma cells in culture. The expressed type III 3-KSR in intact HeLa cells catalyzed the reduction of DHT into 3 beta-diol, whereas expression of type I 3 beta-HSD in these cell lines had no significant effect on the basal conversion of DHT into 3 beta-diol, but it did increase the formation of DHT from 3 beta-diol. A-dione is the predominant product obtained when DHT and 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-diol) are used as substrates in intact JEG-3 and SW-13 cells transfected with rat type I 3 beta-HSD. Furthermore, this predominant 17 beta-HSD activity was also observed in SW-13 cells transfected with the novel rat type IV 3 beta-HSD. The predominance of this 'secondary' 17 beta-HSD activity is also reflected in HeLa cells transfected with type I 3 beta-HSD by the deduced predominant pathway 3 beta-diol-->DHT-->5 alpha-androstane-3 alpha,17 beta-diol (3 alpha-diol)-->androsterone (ADT), in which formation of 3 alpha-HSD activity of HeLa cells, whereas the other reactions are catalyzed by the type I 3 beta-HSD isoenzyme. This observation thus demonstrates that rat type I 3 beta-HSD may also catalyze the conversion of 3 alpha-diol into ADT through its intrinsic 17 beta-HSD activity. The predominant metabolic pathways observed in the present study could be attributed to preponderant bioavailability of NAD+ and NADPH in the intact transfected cells used.
Mol Cell Endocrinol 1994 Jul
PMID:Formation and degradation of dihydrotestosterone by recombinant members of the rat 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase family. 795 95

To assess the direct effect of androgen on the development of atherosclerosis, we investigated the effect of androgen and its receptor expression in rat vascular smooth muscle cells (VSMC) isolated from rat aorta. We detected the androgen receptor mRNA in VSMC by reverse transcription of the total RNA coupled with amplification of the resulting cDNA by polymerase chain reaction. Binding studies revealed the presence of a single class of binding sites for testosterone (Kd 7.37 nM, Bmax 10.59 fmol/mg protein) and dihydrotestosterone (DHT; Kd 4.89 nM, Bmax 11.37 fmol/mg protein) in VSMC. Measurement of 5 alpha-reductase activity suggested that testosterone is converted to DHT in VSMC (Km 0.36 microM, Vmax 623 fmol/mg protein/h). Moreover, in the present study, DHT significantly stimulated DNA synthesis of VSMC (120-160% of control). The mitogenic activity of testosterone is much less potent than that of DHT. Considering these results, we concluded that androgen may directly accelerate atherosclerosis by stimulating the proliferation of VSMC.
J Steroid Biochem Mol Biol 1994 Aug
PMID:Androgen receptors, 5 alpha-reductase activity and androgen-dependent proliferation of vascular smooth muscle cells. 804 46

NADPH-dependent 3 alpha/beta-hydroxysteroid dehydrogenase (3 alpha/beta-HSD) was purified to apparent homogeneity from testicular cytosol of mature pigs. The purified enzyme catalyzes the conversion of 5 alpha-dihydrotestosterone (5 alpha-DHT) to both 5 alpha-androstane-3 alpha,17 beta-diol and 5 alpha-androstane-3 beta,17 beta-diol. The molecular weight of the enzyme was estimated to be 31 kDa by SDS-polyacrylamide gel electrophoresis and 40 kDa by gel filtration chromatography indicating that the native 3 alpha/beta-HSD is a monomer. The isoelectric point of the purified enzyme was found to be 6.2 by density gradient isoelectric focusing and 6.4 by chromatofocusing. The enzyme reduced both 5 alpha- and 5 beta-DHT, 5 alpha- and 5 beta-dihydroprogesterone, 5 alpha- and 5 beta-dihydrocortisol, prostaglandin E2, 13,14-dihydro-15-keto-prostaglandin E2 and 13,14-dihydro-15-keto-prostaglandin F2 alpha. Moreover, the enzyme caused rapid reduction of other carbonyl compounds including aldehydes, ketones and quinones. The rates of reduction of these compounds are fast relative to the rates of reduction of steroids and prostaglandins. The purified enzyme was inhibited by AgNO3, SH-reagent, quercetin, hexesterol, stilbestrol, disulfiram and divalent cation such as Cu2+, Hg2+ and Cd2+. The two enzymes show certain similarities (e.g. molecular weight, cross-reactivity to a common antibody) and certain striking differences (e.g. pI, effects of various inhibitors and greater enzyme activity towards steroids (neonatal form) or prostaglandins (mature form). Reasons are give for suggesting that these enzymes are closely related to carbonyl reductase.
J Steroid Biochem Mol Biol 1994 Feb
PMID:Purification and characterization of 3 alpha/beta-hydroxysteroid dehydrogenase from mature porcine testicular cytosol. 814 2

Structural changes of the androgen receptor (AR) may contribute to the development of resistance to endocrine therapy in prostatic carcinoma. We have isolated AR cDNA fragments from seven tumor specimens derived from patients with advanced metastatic prostatic tumors. In one specimen obtained from a patient who failed to respond to endocrine and cytotoxic therapy we have detected a point mutation in the hormone-binding domain of the receptor. This AR mutation is a guanine-to-adenine transition at nucleotide 2671 that leads to substitution of methionine for the wild type valine at position 715. It is a somatic mutation because it was not present in the AR genomic DNA fragments isolated from prostatic and testicular tissues of the same patient. The mutant AR was recreated in an expression vector and transiently expressed in COS-7 and CV-1 cells. Hormone-binding assays revealed that the mutant receptor does not differ from the wild type receptor in its ability to bind androgen. The dissociation constant for the synthetic androgen mibolerone was 3 nM for both receptors. There was also no significant difference in binding of other steroids and nonsteroidal antiandrogens as revealed by competition binding assays. However, transfection experiments to determine the trans-activation potential of the mutant receptor produced differences in the action of this receptor compared to the wild type receptor. Dihydrotestosterone and the synthetic androgens methyltrienolone (R1881) and mibolerone were equally proficient in conferring trans-activation activity to both the mutant and wild type receptors. Adrenal androgens such as dehydroepiandrosterone and androstenedione, as well as progesterone mediated a higher trans-activation through the mutant than through the wild type receptor. These data demonstrate that the exchange of a single valine into methionine at position 715 in the AR promoters trans-activation not only by testicular but also by adrenal androgens and progesterone. This pattern of ligand-dependent trans-activation may have significance in the process controlling the progression of prostatic carcinoma.
Mol Endocrinol 1993 Dec
PMID:Mutant androgen receptor detected in an advanced-stage prostatic carcinoma is activated by adrenal androgens and progesterone. 814 61

Casein kinase 2 (CK-2) is a ubiquitous messenger-independent protein serine/threonine kinase that has been implicated in the control of cell growth and proliferation. By employing androgen action in the prostate as a model of growth control, we have previously documented that androgens modulate prostatic CK-2 activity in a tissue specific manner. Here we have investigated the role of transcriptional control of prostatic CK-2 in androgenic regulation of its activity. We first cloned and sequenced full length cDNAs encoding the alpha and beta subunits of rat CK-2. The cDNA sequence encoding the alpha subunit corresponded with previously reported sequences for other species, as well as with the derived partial amino acid sequence reported for a rat cDNA. The cloned cDNA for rat CK-2-beta subunit, not reported previously, was also identical in amino acid sequence to that of other species. The cDNAs for alpha and beta subunits were employed as probes to examine the effects of altered androgenic status on transcription of mRNAs for the subunits of prostatic CK-2. Androgen deprivation caused a slow decline in transcription of the a subunit, so that no change was noted at 24 h postcastration; however, at later periods of androgen deprivation a progressive but relatively slow decline was apparent. Administration of a single dose of 5 alpha-dihydrotestosterone (5 alpha-DHT) to 6-d castrated animals did not elicit an early expression of new mRNAs for CK-2-alpha and beta subunits. However, a significant expression of mRNAs for the two subunits was apparent at 8 h (i.e., later stages of the prereplicative phase) reaching a peak in the proliferative phase of prostatic growth (i.e., at 24-48 h) following androgen administration. These data suggest that androgenic regulation of CK-2 gene transcription is not an early event related to androgen action, but is substantial in the prereplicative phase of prostatic cell proliferation mediated by androgen. Further, androgenic stimulation of the mRNA expression for the alpha and beta subunits of CK-2 appears to be differential.
Cell Mol Biol Res 1993
PMID:Cloning of cDNAs encoding the alpha and beta subunits of rat casein kinase 2 (CK-2): investigation of molecular regulation of CK-2 by androgens in rat ventral prostate. 817 90

This paper summarizes the most recent data obtained in the authors' laboratory on the metabolism of testosterone and progesterone in neurons, in the glia, and in neuroblastoma cells. The activities of the 5 alpha-reductase (the enzyme that converts testosterone into dihydrotestosterone, DHT), and of the 3 alpha-hydroxysteroid dehydrogenase (the enzyme that converts DHT into 5 alpha-androstane-3 alpha, 17 beta-diol, 3 alpha-diol) have been first evaluated in primary cultures of neurons, oligodendrocytes and type-1 and -2 astrocytes, obtained from the fetal or neonatal rat brain. All the cultures were used on the fifth day. The formation of DHT of 3 alpha-diol was evaluated incubating the different cultures with labeled testosterone or DHT as substrates. The results obtained indicate that the formation of DHT takes place preferentially in neurons; however, type-2 astrocytes and oligodendrocytes also possess considerable 5 alpha-reductase activity, while type-1 astrocytes show a much lower enzymatic concentration. A completely different localization was observed for 3 alpha-hydroxysteroid dehydrogenase; the formation of 3 alpha-diol appears to be prevalently, if not exclusively, present in type-1 astrocytes; 3 alpha-diol is formed in very low yields by neurons, type-2 astrocytes and oligodendrocytes. The compartmentalization of two strictly correlated enzymes (5 alpha-reductase and 3 alpha-hydroxysteroid dehydrogenase) in separate central nervous system (CNS) cell populations suggests the simultaneous participation of neurons and glial cells in the 5 alpha-reductive metabolism of testosterone. Subsequently it has been shown that, similarly to what happens when testosterone is used as the substrate, the 5 alpha-reductase which metabolizes progesterone into 5 alpha-pregnane-3,20-dione (DHP) shows a significantly higher activity in neurons than in glial cells; however, type-1 and -2 astrocytes as well as oligodendrocytes also possess some ability to 5 alpha-reduce progesterone. On the other hand, 3 alpha-hydroxysteroid dehydrogenase, the enzyme which converts DHP into 5 alpha-pregnane-3 alpha-ol-20-one, appears to be present mainly in type-1 astrocytes; much lower levels of this enzyme are present in neurons and in type-2 astrocytes. At variance with the previous results obtained using androgens as precursors, oligodendrocytes show considerable 3 alpha-hydroxysteroid dehydrogenase activity, even if this is statistically lower than that present in type-1 astrocytes. The existence of isoforms of the enzyme involved in androgen and progesterone metabolism is discussed.(ABSTRACT TRUNCATED AT 400 WORDS)
J Steroid Biochem Mol Biol 1993 Dec
PMID:Androgen and progesterone metabolism in the central and peripheral nervous system. 827 36

Female newborn mice were given daily injections of estradiol-17 beta (E2; 25 micrograms/mouse/day) for 4 days from the day of birth, and uterine cell death after this E2 priming was investigated by examining the apoptotic index (percentage of apoptotic cells), and the retention of 3H-radioactivity incorporated into epithelial or stromal DNAs after injection of [3H]thymidine into the mice on the day after birth. With injections of vehicle only after E2 priming, the apoptotic index of the uterine epithelium increased markedly, being maximal on day 4 of injections, and the 3H-radioactivity retained in the epithelium decreased rapidly. Agarose gel electrophoresis of uterine epithelial DNAs on day 4 of injections showed a ladder pattern, characteristic of apoptotic cell death. However, daily injections of E2 (7.2 micrograms/g body wt) completely inhibited the increase in the apoptotic index and the loss of 3H-radioactivity in the epithelium. Daily injections of progesterone (80 micrograms/g body wt), 5 alpha-dihydrotestosterone (DHT; 8 micrograms/g body wt), and dexamethasone (2 micrograms/g body wt) also inhibited both parameters, although not completely. The inhibitory effects of DHT and progesterone were abolished by the antiandrogen, flutamide and antiprogesterone, RU 486, respectively. In contrast, no apoptotic cells and no loss of 3H-radioactivity were found in the stroma for any treatment after E2 priming. The present results suggest that discontinuation of estrogen stimulation results in apoptotic cell death in the uterine epithelium of neonatal mice, but not in the stroma, and that estrogen, progesterone, DHT and dexamethasone inhibit cell death of uterine epithelium.
J Steroid Biochem Mol Biol 1993 Jul
PMID:Inhibitory effects of estrogen, progesterone, androgen and glucocorticoid on death of neonatal mouse uterine epithelial cells induced to proliferate by estrogen. 833 88

The specific activity of 17 beta-hydroxysteroid oxidoreductase (17-HOR) with estradiol-17 beta (E2), estrone (E1) and testosterone (T), as well as that of lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) were measured in homogenates of CF-1 mouse placenta during the latter half of pregnancy. 17-HOR activity with E2 and T increased over 100-fold between days 9 and 12, and 3- to 4-fold between days 15 and 19, with no further change to day 21. In contrast, activity with E1 increased 39-fold between days 9 and 12, 3.8-fold between days 15 and 19 but then decreased between days 19 and 21. The E2/T activity ratio was constant while the E2/E1 ratio increased between days 9 and 21. LDH increased 2-fold between days 9 and 12 with no further increase to day 19. MDH was constant from day 9 to 19. Activity with E2 was inhibited by T, 5 alpha-dihydrotestosterone (5 alpha-DHT) and DHA but not by E1, androstenedione (A) or 20 alpha-dihydroprogesterone. Activity with T was inhibited by E2, 5 alpha-DHT and DHA, but not by A. In contrast, activity with E1 was inhibited by A and DHA but not by E2, T or 5 alpha-DHT. The results suggest placental 17-HOR is developmentally regulated. Although the results are also suggestive of multiple forms of 17-HOR, a single enzyme with an ordered kinetic mechanism cannot be ruled out.
J Steroid Biochem Mol Biol 1993 Jul
PMID:Placental 17 beta-hydroxysteroid oxidoreductase, lactate dehydrogenase and malate dehydrogenase during the latter half of pregnancy in the mouse. 833 91


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